[big black dogs]

Thanks for posting. Some of the stuff up there is not true or the thinking has changed. Keeping a female intact till 4 years of age has a high chance of developing pyometra as well as mammary cancer. I would NOT keep a pet female intact till 4 years of age unless you are showing and breeding. Waiting till a female has gone through a couple of heats and has matured through their hormones is probably a better choice for a pet owner. Giving dogs a chance to grow up and develop with their hormones is the way to go. Some pet owners are not responsible and that is often why vets push earlier spay/neuter.